Holding and gripping device for tension compression springs



Feb. 16, 1965 J. RGDER ETAL 2 Sheets-Sheet 1 Filed June 19, 1962 S m a T Z mmw me W n w M J m m m j 1 l 9 i 4 W [L JJ v f p Q v. J 11 E 7 /7 E252; J5 J Feb. 16, 1965 J. RODER ETAL HOLDING AND GRIPP ING DEVICE FOR TENSION-COMPRESSION SPRINGS 2 Sheets-Sheet 2 Filed June 19, 1962 HI I l a J M ,6 & z J .N m 2 u eeNne w/M a 0 H E 7 0 L z 6 I N B K MU in 2 W301: W m l AA w M l n' H-5,

United States Patent 3,169,757 HOLDENG AND GRIPE'ING DEVICE FUR TENSFON- C(DMPRESSIGN SPRENGS Josef Riider and Georg Klein, Darmstadt, Karl-Heinz Kiinzel, Darmstadt-Eberstadt, and Paul Kriiger, Darinstadt-Arheilgen, Germany, assignors to Carl Schenck Maschinenfahrik G.m.b.ib'i., Darmstadt, Germany, a German eompan Filed June 19, 1962, Ser. No. 293,568 Claims priority, application Germany, June 24, 1961,

Sch 29,910 r 7 Claims. (Ci. 26760) The invention disclosed herein is concerned with a holding and gripping device for springs, for example, helical springs or springs of the frustum type, which are subjected to tension and to compression.

While a spring which is only subjected to' compression may lie relatively looselyin holding plates provided there for, a spring which is subjected to tension and to compression, must be firmly held and gripped at the ends thereof. It is known to wind the terminal ends of a tension spring on a suitable mandrel-like or similar gripping member which is provided with grooves formed therein, the corresponding turns'of the spring lying in the grooves secured against slippage, being thus firmly gripped in fixed position thereof. In the actuation of such fixedly gripped springs, the shearing stresses becomefully operative at the fixedly gripped wire. This increases the danger of spring breakage, and tension-compression springs provided with such holding and gripping devices have therefore not gained favor in practical use.

The object of the present invention is to provide 'a spring holding and gripping device which avoids the drawbacks of the previously known devices.

According to the invention, this object is realized by the provision of a spring holding and gripping device which is so constructed that the reactive forces, exerted by the gripping device on the spring turns which are being gripped, and acting counter to the spring loading,

diminish progressively in the direction of the'spring turns which are not being gripped. 1

In a holding and gripping device constructed in this manner, the transition of the shearing stresses acting on i the spring wire responsive to the load, as well as the pressure stresses exerted by the gripping device, do not operate suddenly but gradually progressively, the consequently more favorable stress distribution reducing to a great extent the danger of spring breakage.

The spring holding and gripping device according to an embodiment of the present invention, comprises a gripping ring formed of a plurality of parts and disposed Within the spring turns to be gripped, such ring forming grooves for receiving the corresponding spring turns, said grooves becoming wider and flatter in the direction of the part' of the spring which is not being gripped, and means for tensioning the ring with respect to the gripped spring turns, so as to apply radial pressure thereto. A screw device is advantageously used as a tensioning means, cooperating with a centrally disposed conical ring which is pressed into the gripping ring so as to spread such ring radially apart to apply pressure to the corresponding spring turns. The configuration of the grooves which receive the spring turns secures the progressively gradual transition of the shearing stress.

The inwardly gripped spring turns are radially outwardly surrounded by a fixed tubular member to which is attached a radially extending plate-like member forming therewith a cup-shaped spring holder. 7 p

In accordance withanother feature of the invention, an outer tensioning or spring gripping ring may be used in place of the above noted cup-shaped holder, and an outer Patented Feb. 16, 1965 In accordance with a further embodiment of the inven- I tion, there is provided a resilient body, for example, a rubber body, disposed within the spring turns whichare to be gripped, said rubber body having a wedge-shaped core of solid material, for example, a core made of iron. The Wedge shaped core is embedded in the rubber body and is adjustable with respect thereto, so that the gripping forces exerted by the rubber on the corresponding spring turns diminish in the direction of thespring turns which are not being gripped.

It is in accordance with still anotherembodiment possible to use a spring gripping member of rubber without the rigid core.

reference to the accompanying drawings, showing embodiments .thereof.

FIG. 1 shows an embodiment using an inner tensioning member made of a plurality of parts, which may be radially spread apart or expanded to apply gripping pressure to spring turns to be gripped;

FIG. 2 represents an embodiment employing in addition to the inner tensioning or spring gripping member an outer complemental annular spring gripping member made of a plurality of parts, andmeans for radially inwardly tensioning or contracting such outer member to apply gripping pressure to the corresponding turns of a p g;

FIG. 3 indicates an embodiment employing "a rubber member for gripping the turns of aispring, said rubber member having a core of rigid material for adjusting the spring gripping pressure; and

FIG. 4 shows an embodiment likewise utilizing a rub her body for gripping turns'of a spring, omitting the core of rigid material, and having means for adjusting the gripping pressure of the rubber body.

The illustrated examples of the invention show devices for holding and gripping cylindrical helical springs. Howeven'the invention is likewise applicable in connection with other'kinds of springs, for example, springs'in the shape of a frustum or the like. 7 If desired, two

The embodiment shown-in FIG. -1 comprises a tubular conical tensioning or adjustingmember 2, through the bore of which extends a screw device serving'as an adjusting means, such device comprising a threaded bolt 3 and a nut 4. Thetubular conical tensioning member 2 cooperates with a tensioning or spring gripping ring 5 which is preferably made of three parts which are provided on the outside thereof with thread-like grooves 6 conforming to the pitch of the terminal turns 9 of the spring 1. The grooves 6 become progressively broader and flatter in axiallyinward direction, that is,1'in the direction of the part of the spring 1 which is notbeing of the turns 9 of the spring 1 lie in the respective grooves rigid 'materiahfor examplefi'iron or the like.

"rubber body 23.

" toexert pressure against thejspring' turn 1n grooves'34'produc'edthereby. I t 1 6, While such turns are on the radially outwardly facing sides thereof in engagement with the inner wall of ii a fixed tubular member 7, .the latter being connected 'witha plate-likemeinberS and forrning with such plate like member the holder for the spring 1. Responsive to a compression force, acting on the spring 1, the spring turns 9 will be in more or less pressure engagement with the flanks of the respective grooves 6 which face toward the holder plate 8. Responsive to tensile force acting on the spring 1, the spring turns 9 will be in pressure engagernent with the flanks'of the grooves 6 which face away from the plate Sor axially inwardly of the structure Referring now to FIG. 2, and particularly to the spring holding and gripping device shown at the bottornthereof, there is provided a centrallydisposed tensioning or spring gripping ring 5, again comprising a plurality of parts, which may be. radially expanded bythe action of-the conical member 2;, which is axially adjustable by the screw is no sudden transition withrespect to the spring gripping 1 and holding forces. The thread-like grooves, panicularly device 3, 4, cooperating with the pressure plate 11, to

apply radially outwardly ettectivei pressure forceto the radially inwardly facing sides of :the spring turns 9.

, outer tensioning or spring gripping ring 12., likewise comprising a plurality of parts, preferably three parts, surrounds the spring turns 9 onthe outside thereof. The

outer spring gripping'ring 12 is provided with angular radiallyoutwardly facing surfaces which are in cooperative engagement with correspondingly angularly shaped inner Walls of a fixed outer ring 16 through the'bores of 'wln'ch extend screw devices comprising respectively threaded bolts 14 and nuts 15. The bolts 14 act upon the outer ring 12 through the medium in an axially inwardly disposed pressure plate 13, causing the spring gripping ring 12 to contract radially inwardly so asto,

exert a supplemental gripping. force on, the, spring turns 7 9. The fixed ringld is fastened to the -holder plate The spring holding and gripping device shownat the V in thedrawings.

top of FIG. ZCorresponds generally to the above described gripping device shownat the bottorncf the figure, except that both; the inner spring gripping ring S and the outer spring gripping ring 12 are provided with grooves respectively indicatedat 6 and 13, for receiving the spring turns 9 to be gripped; The grooves again become wider and flatter. axially inwardly or toward the part 'ofthe spring Lwhich is-not being gripped. i

The spring holding :and gripping device indicated in in such lining groovesfi? in which" the spring turns are gripped. The tubular member is fixedly attached t the plate 33, for example, by welding.

The rubber bodies 23and 31 shown respectively in FIGS. 3 and 4, may be made of relatively soft material. The rigid core: 22 (FIG. 3) .must be made of material with relatively" great strength. Iron and hardened synthetic maierials or the like' may be used for this purpose.

In the event that the bodies 23 and 31, or the linings 27,

will be of advantage to form therein grooves corresponding'as topit-ch and depth to the respective spring turns.

The feature wmch distinguishes the spring holding and gripping device of the present invention from previously spring turns into the rubber lining 36, thus producing 36, respectively, are'made of relatively hard rubber, it

known devices o'i 'this general lzind'resides in that there 7 as they are presentin the embodiments according to FIGS. 1 and 2, areof aconiiguration such that there is no sharp distinction; between inactive and 'operatively eliective spring turns. The spring which, is'statically and dynamicaliy stressed can attach itself to the grooves which becomewider and flatter, or liftoff from thev grooves,fq;le-v

pending uponthe load placed on thespring. The grip.- ping torces'can'becontinuously adjusted to given operating requirements by the screw adjusting devices shown The-rubber body acting in the embodiments according to FIGS, 3. and 4 as a gripping elementis responsive to tightening of the adjusting screw deformed laterally outwardly into pressure engagement with the springturns, moving also-between the spring turns. This provides for device as to force and configuration thereof.

The cons shaped core 22- used in the embodiment shown in FIG; 3, is operative to provide for a displacement of the cup-shaped rubber. body 23 so that the wall -thereof increases in thickness in. the direction of the part.

of the spring l which is not being gripped. The thicker the wall of the rubber body is, the betterwill such body] coact with the actration of the spring turns. Thegradual transition from the rigidgripping ot the springto the free,

FIG. 3 comprises arubber body 23 having a core .22 of I The grippmg force exerted by the rubber body 23 on the spring turns 9 may be adjusted by means of a screw devicecom prisinggtor example, a threadedbolt 3 and aznut 'd.

Thefonce produced by thescrew'device is transmitted to the core 22 by the pressure platezll, :Tightening of The-spring; holding and gripping structure shown in the upper part of FIG. 3 comprises a platelike' member 24 provided witha tubular member 26 fixedly attached thereto, such member being'provided with a rubber lining '27i 1nto which the spring turns 9am pressedldependin'g' on the force exerted upon suchspringturns by the inner the nut 4 presses the rubbenbody 23 radially outwardly. I I The spring turns of the spring I produce. in therubberi; 1 fbody 2 3 grooves 2 5..for holding'the spring turns 91.

The embodiment according toiFlGi' 4 utilizesa rubber i body SL-as a spring grippingandtensioning element.

' The core 22 of rigid material, used in FIG. 3, is omitted a 1n theembodiment according to FIG. 4." The 'f orcepro duced bythescrew devicer3,;4'acts' through the medium of the pressure plate 32 directly on the rubber body 31 1 to cause lateraldeformati-on.of u h rubber body 1,

- s9 :which nestle As s ow n the op part for FIG. 4. there'maya'gain be provided a fixed outer' tubular. rnember35 .linedfwith rubber asindicated at 3 6'. i The lateral pressure 'exertc-ldon the' spring turns the rubber body 31 presses these,

mobility thereofis thereby benefitted." a iChanges may be made within the scope and spirit of the appended claims'which define what is believed to be new and desired to have protected by Letters Patent.

We claim; j 5

. .1. A holding and gripping V are. subjected to tension and to compression, comprising radially :outwardlyexpansible gripping means disposed within a spring in pressure engagement with iterminal turnsof said spring on thejinside thereof, means engageable 'with said gripping means for. adjusting the radially.

" outwardly effective pressure exerted by saidfgripping means on said spring turns, said gripping device being spring and diminishes progressivelylinaxially extending inward direction toward thespring turns which are .free of'sai gripping means, said gripping device comprising an annularradiallyputwardly expansible; niember coi posed of a. plurality "of -:part s, grooves being formed in said parts/for receiving the terminal turns of said springs,

device for springs which,

a connection of thesp ringw ith the parts of the gripping r constructed to exert a reactive force on said spring turns which counters the force exerted bytheloadon'the the width of said grooves increasing and the depth thereare free of'saidgripping device.

1 of decreasing in the direction of the spring turns which. 7

constructed to exert a reactive force on said spring turn which counters the force exerted by the load on the spring and diminishes progressively in axially extending inward direction toward the spring turns which are free of said gripping means, said gripping device comprising an annular radially outwardly expansible member composed of a plurality of parts, grooves being formed in said parts for receiving the terminal turns of said springs, the width of said grooves increasing and the depth thereof decreasing in the direction of the "spring turns which are free of said gripping device, and a iixed tubular member surrounding said spring turns on the outside thereof. a

3. A holding and gripping device for springs which are subjected to tension and to compression, comprising radially outwardly expansible gripping means dispose-d ithin a spring in pressure engagement with terminal turns of said spring onthe inside thereof, means engageable with said gripping means for adjusting the radially outwardly effective means on said spring turns, said. gripping device cons ructedto exert a reactive force on said spring turns which counters the force exerted by the leader. the spring T and diminishes progressively in axially extending inward direction toward the spring turns which are free of said gripping means, said gripping means comprising a rubher body, screw operated meansfor adjusting the pres-' sure of said rubber body exerted on said springturns,

and a fixed tubular member lined with rubber and surrounding said spring turns on the outside thereof,

4. A holding and gripping device for springs which are subjected to tension and to compression, comprising radia ly outwardly expansible gripping means disposed within a spring in pressure engagement with terminal turns of said spring on the inside thereof, means engageable with said gripping means for adjusting the radially outwardly efiective pressure exerted by said gripping 'nieans on said spring turns, said gripping device being constructed to exert a reactivefforce on said spring turns which counters the force exerted by the load-onthe spring and diminishesprogressively in axially extending inward direction toward the spring turns which are free of said gripping means, said gripping means comprising a rubber body, screw operated means for adjusting the pressure of said rubber body exerted on said spring turns,

a conical core disposed within said rubber body, said 1 pressure' exerted by said gripping eing core being made of a material having an elasticity less tnan that of said mbber'body, and a fixed tubular member lhied wi h rubber and surrounding said spring turns on the outside thereof.

5. A device according to claim 1, comprising a second annular radially inwardly contractible member composed of a plurality of parts provided with grooves for receiving said terminal turns of said spring on the outside thereof,

said grooves likewise increasing in width and decreasing in depth in the direction of the spring turns which are rree o" gripp'ag device, and means for adjusting t e radi lly inwardly eifective pressure exerted by said aid spring turns.

. o. A device according to claim'S, wherein the respec p ,7 A device according to claim 1, comprising a second annular radially inwardly contractiblemember composed of a plurality of parts provided with grooves for receiving said terminal turns ot said spring on the outside thereof,

said grooves likewiseincreasing in widthand decreasing in depth int'ne direction of the spring turns which are a I free of said gripping device; a fixed outer member. surrounding secondtannular member, and means coopera mg with said fixed outer-member forjadiusting the radially inwardly effective pressure exertedby said second member on the radially outwardly facing sides of said spring turns.

References fired in the of this patent I UNITED STATES PATENTS 51,368

Vose Dec. 8, 1865 1,464,464 Meyer Jan. 24, 1922 1,610,770 Greene Dec. 14, 1926 1,544,783 Lissel Och-11, 1927 2,646,950 Nelson et al. June 18, 1953 3,941,660 Jacobson lune 26, 1962 roaarGN PATENTS 213,725 7 Austria Dec. 29, 1959 336,633

econd men her on the radially outwardly facing sides of a Switzerland Apr. 15, 1959' 

1. A HOLDING AND GRIPPING DEVICE FOR SPRINGS WHICH ARE SUBJECTED TO TENSION AND TO COMPRESSION, COMPRISING RADIALLY OUTWARDLY EXPANSIBLE GRIPPING MEANS DISPOSED WITHIN A SPRING IN PRESSURE ENGAGEMENT WITH TERMINAL TURNS OF SAID SPRING ON THE INSIDE THEREOF, MEANS ENGAGEABLE WITH SAID GRIPPING MEANS FOR ADJUSTING THE RADIALLY OUTWARDLY EFFECTIVE PRESSURE EXERTED BY SAID GRIPPING MEANS ON SAID SPRING TURNS, SAID GRIPPING DEVICE BEING CONSTRUCTED TO EXERT A REACTIVE FORCE ON SAID SPRING TURNS WHICH COUNTERS THE FORCE EXERTED BY THE LOAD ON THE SPRING AND DIMINISHES PROGRESSIVELY IN AXIALLY EXTENDING INWARD DIRECTION TOWARD THE SPRING TURNS WHICH ARE FREE OF SAID GRIPPING MEANS, SAID GRIPPING DEVICE COMPRISING AN ANNULAR RADIALLY OUTWARDLY EXPANSIBLE MEMBER COMPOSED OF A PLURALITY OF PARTS, GROOVES BEING FORMED IN SAID PARTS FOR RECEIVING THE TERMINAL TURNS OF SAID SPRINGS, THE WIDTH OF SAID GROOVES INCREASING AND THE DEPTH THEREOF DECREASING IN THE INCREASING AND THE DEPTH THEREARE FREE OF SAID GRIPPING DEVICE. 